1. Field of the Invention
The present invention relates to an optical waveguide for a luminescent device for ornamental or other purposes, and a manufacturing method thereof.
2. Description of the Related Art
Heretofore, a light emitting board using an optical waveguide has been proposed as a light emitting board which can be used for ornamental objects and the like (see Japanese Patent No. 2814684). This light emitting board includes a linear light guiding portion (a core) formed on a substrate, and a low refractive portion (an over cladding layer) formed on the above-mentioned substrate so as to cover the light guiding portion (the core). The refractive indices of the above-mentioned substrate and the low refractive portion (the over cladding layer) are lower than the refractive index of the light guiding portion (the core). A light scatterer is dispersed in the above-mentioned light guiding portion (the core) to cause light beams propagating through the above-mentioned light guiding portion (the core) to change their optical paths upon impingement upon the above-mentioned light scatterer. Some of the light beams which change their optical paths toward the surface of the above-mentioned low refractive portion (the over cladding layer) cause the light emission from the above-mentioned light emitting board in a linear configuration which is the configuration of the light guiding portion (the core).
In the above-mentioned light emitting board, however, the low refractive portion (the over cladding layer) having the refractive index lower than that of the light guiding portion (the core) covers the light guiding portion (the core) through which the light beams propagate. It is therefore difficult for the light beams propagating through the above-mentioned light guiding portion (the core) to travel toward the low refractive portion (the over cladding layer). In other words, the above-mentioned light emitting board is low in outward light emission efficiency.